Low Oxygen Brewing-Summarized for the Homebrewer

Low oxygen brewing is common practice for breweries in
Germany and other places around the world.
This style of brewing reduces or eliminates oxygen throughout the entire
brewing process, from doughing-in to packaging.
In their paper entitled, “On Brewing Bavarian Helles: Adapting to Low
Oxygen Brewing”, the team at the German brewing forum purports that, “it takes
less than 1 minute of oxygen exposure in excess of 1 ppm to completely rob the
beer of the fresh malt flavor”.

For the
homebrewer, that means some serious thought needs to be put into our brewing
systems and procedures before we can hope to attain dissolved oxygen levels as
low as that.

Most of us homebrewers will not go out and purchase any expensive new
equipment to accommodate this new style of low oxygen brewing (new to us at least). But, from what I have read, the only
purchase you will have to make is to get rid of or sell your old copper
immersion chiller or copper plate chiller and purchase stainless steel. Apparently copper, iron, zinc and manganese
accelerate the oxidation of malts.

These
reactions involve way too much chemistry for me to include in this article, so
if we take the German brewing forum team’s word for it, then we need to eliminate
all copper from our brew systems if we want to brew with the low oxygen brewing method.

Realizing that we homebrewers are as a group,
cheap, we are also perfectionists when it comes to making beer. We want to brew the absolute best beer
possible within the limitations of the equipment and processes that we can
employ as homebrewers.

So, with that in
mind, I don’t think replacing an IC would be overly expensive if we knew we
could brew much better malt forward (typically German style) beers.

Most of the changes homebrewers will have to
make to employ low oxygen brewing are easily achievable with only minor alterations to procedures and
equipment.

I have not had a chance to verify any of the information in
the paper, but from what I’ve read, other brewers have successfully recreated
the results.

To me the effort to
eliminate or reduce the amount of dissolved oxygen in our brewing process is definitely
worth doing as we all know about oxygen’s effect on shelf life and staling of
our beers. Employing the LODO brewing method will, however, add some time
to an already long brew day.

I’ve summarized some of the main points in the article that
are relevant to homebrewers in the table below:

The major problem for homebrewers wishing to try
low oxygen brewing is that the malt is already oxidized before we finish
doughing-in because our strike water is saturated with oxygen. Our
cold tap water or the cold water coming out of our RO system is saturated with
8-12 ppm of dissolved oxygen.

If you can smell malt aromas at any time during
your hot-side process (while your wort is above 140°F or 60°C) then those aromas
and flavors will no longer be available in your finished beer. Using low oxygen brewing will result in your mash and boil having much less of the malt aromas you are used to.

At typical mash temperatures of 145-160°F (63-71°C),
the solubility of oxygen in water is about 4-5 ppm.

Pre-boiling and rapidly chilling your brewing
water will reduce the dissolved oxygen level to less than 0.5 ppm.

With current homebrewing procedures, doughing-in
will add approximately 1-3 ppm of dissolved oxygen to your wort.

Between 1-2 ppm of dissolved oxygen will diffuse
into your wort from the atmosphere per hour.

1 ppm of dissolved oxygen present at any time
during the “hot side” of your process is enough to remove the fresh malt flavors
from your beer.

The process of hot-side oxidation (HSO) results
in both the loss of malt flavor and the creation of staling compounds in your
finished beer.

HSO in low oxygen brewing occurs many times faster for the homebrewer
compared to a commercial operation due to the increased surface area exposed to
oxygen. A typical commercial brewery’s
surface area to volume ratio (of 26,417 gallons or 1000 hectoliters of wort) is
20 times less than a homebrewer’s normal 5 gallon batch size.

HSO in the mash will begin within seconds and
the peak reactions will occur within the first 30 seconds to 1 minute after
doughing-in. This is why it is so
important to get the dissolved oxygen level in your strike water as close to
zero as possible prior to adding your grain.

In commercial breweries in Germany and other
places around the world which use the low oxygen brewing method, the grain is added first and the hot strike water is
introduced from below. For homebrewers
this may not be possible, depending on the design of your brewing system.

Normal homebew kegging procedures will pick up
around 0.8-1 ppm of dissolved oxygen (DO).
So, it’s important to use the recommended purging procedures in step 18
below.

Low Oxygen Brewing Steps for the Homebrewer

Oktoberfest and German Beer from a Boot

If we as homebrewers wish to use low oxygen brewing, then to remove oxygen at the homebrew level means that we must
eliminate all sources of dissolved oxygen and oxidation accelerants (ie. Copper)
as well as employ the use of oxygen scavengers.

I’ve gone through the article on low oxygen brewing and pulled out the steps we as homebrewers
can easily employ to make better German style beers using the low oxygen brewing
method:

1.
Remove
the oxygen from your strike water by pre-boiling
the strike water immediately before use by boiling it vigorously for 5 minutes and
quickly chilling it down to strike temperature.
An immersion chiller (IC) works best but using a copper IC is not
recommended because the copper accelerates oxidation of the malts.

2.
Add
Sodium Metabisulfite (SMB) (not potassium metabisulfite) as an oxygen
scavenger to control the ingress of oxygen.
Excess sulfites will be consumed by the yeast during fermentation and
the final level of sulfites in your homebrew will be consistent with those in
commercial German beers. FYI: Sulfite
levels in most commercial beers that come from normal fermentation processes will
typically be in the 10-15 ppm range.

3.
Use reverse
osmosis (RO) water, adding enough calcium chloride to produce 30-50 ppm
calcium. In your water addition
calculations, account for the fact that each mg/l of SMB will add 24 ppm of
sodium to your water. The same concentration
will also add 76 ppm of sulfur compounds in the form of sulfates, sulfur
dioxide, and bislufite. The amount of
sulfate added is more difficult to calculate because it depends on the amount
of oxygen introduced and subsequently removed by the oxygen scavenger.

4.
The team at the German brewing forum recommends that
you add 100 mg/l of SMB in the mash
water and 10-15 mg/l of SMB in the sparge water for low oxygen brewing.

The amount of sodium and sulfates added from
the addition of SMB will depend on the ratio of mash water to sparge water in
your recipe. Be aware that this is a starting volume of SMB
and will need to be adjusted as you brew subsequent batches. If you notice excess sulfur in your finished
beer, reduce the addition of SMB in your next batch.

Also be aware that different strains of yeast
will utilize or tolerate sulfate levels differently, especially when comparing
lager yeasts to ale yeasts.
Experimentation will be needed to optimize the amount of SMB added to
your system.

5. If you brew with a no-sparge process,
reduce the amount of SMB from 100 mg/l to 55 mg/l.

6.
If you cannot get powdered SMB, a campden tablet will supply 440 mg of
metabisulfite per tablet. Campden
tablets are readily available at all homebrew and winemaking supply
stores.

Crush the campden tablets if
using them, or add the powdered SMB to the strike water and let it set for no
more than 5 minutes prior to doughing-in to allow the metabisulfite to scavenge
the available dissolved oxygen.

As a rule
of thumb, it takes about 5 ppm sulfite to scavenge 1 ppm of oxygen from your
water.

7.
If you cannot add your grist to an empty mash
tun and introduce the strike water from below (which many of us won’t be able
to do), then add the strike water first
with as little splashing as possible then add the grain from above slowly
and while gently stirring.

It is
critical not to add the grist too quickly or stir too vigorously which will
aerate the wort. If your grains are
floating on top of your strike water, then you have air
trapped in your grain that will be incorporated while you dough-in. Too much oxygen introduced here will not only
oxidize the malt but also consume a large amount of the SMB in the strike
water.

8.
Mash for
as little time as possible. Check
for starch conversion by draining from below.
A good DIY project to reduce the head space and thus the oxygen above
the mash would be to design a mash cap or a lid that can sit just above the top
of the mash. If nothing else, how about
laying plastic wrap such as Saran Wrap on top of your mash and don’t remove it
until you clean your mash tun.

Dissolved Oxygen Meter

9.
If you
use pumps in your system, which most RIMS and HERMS systems will, double check all connections and fittings
for leaks. Another good DIY project
would be to figure out a way to pressurize your service lines and check for
leaks with a spray bottle of soapy water.

By adding a drilled rubber “cork” that fits
inside your discharge line, you should be able to insert the end of the CO2
blow gun in the “cork” and pressurize your lines while someone else sprays the
connections and fittings with soapy water, looking for bubbles.

If you can purchase a dissolved oxygen
meter, checking your pre-boiled strike water before and after circulating for a
few minutes should indicate if there are any leaks.

You will notice the DO levels rise due to an
ingress of oxygen into your system. DO
meters are expensive. The cheapest
models I found on Amazon were in the $155 range.

10.
If using
pumps to move your strike water and wort, keep the flow rate low, around 3-4
liters per minute (about 1 gpm). If
you use propane burners to heat your mash (which most homebrewers will), you
may need to bump up the flow rate to 6-8 liters/minute (1.5 to 2 gpm) to get
even heating and to prevent scorching. Make
sure the return line is below the top of the mash to prevent splashing and
aerating the wort.

11.
When lautering, a no-sparge process is best to minimize oxygen ingress in your
wort. If you feel you must sparge, you
will have to treat your sparge water just like your mash water. It must be pre-boiled and quickly cooled down
to sparge temperature.

You must also add
SMB at the rate of 10-15 mg/l. When
sparging, you have to add the water gently to the top of the mash without
splashing or aerating the mash in any way.

So, you may have to alter your sparge equipment if you use a sprinkling
sparge arm or one with siphon sprayer.
Try running your tubing and laying it directly on top of or below the
surface of your mash.

12.
Try adding
a portion (30%) of your bittering hops as first wort hops (FWH) directly to
the boil kettle during the lautering process, allowing them to steep while the
sparge finishes. The German brewing
forum guys have had great success with FWH in a LODO.

13.
Use a 60
minute gentle boil, no more than a simmer.
The evaporation rate should be in the 8-10% range. This evaporation rate should be sufficient to
prevent DMS from entering your finished beer.

14.
Chill the
wort as rapidly as possible to fermentation temperature without aerating
it. This may be one of the most
difficult alterations to the normal brew day that homebrewers will encounter
when trying to brew with LODO.

For those
using coolers who manually chill with an immersion chiller, some drastic
alterations in the chilling process is in order. I normally have to stir the wort vigorously
around the IC to get the wort cooled in a timely manner.

Any suggestions here would be welcomed by homebrewers
who also use this method of chilling their wort. Most homebrewers would rather alter the
mechanics rather than their equipment to save money.

15.
You can allow the cold break material to
enter the primary fermenter, but avoid letting the hot break or hop trub
into the fermenter.

16.
Consider
the yeast as your best defense against oxidation. Getting the yeast into the fermenter as
quickly as possible is a must. Mix the
yeast in the wort well and add oxygen to the wort only after the yeast has been
added, trying for about 8 ppm DO.

17.
You want to transfer
your wort to a secondary fermenting keg when it reaches 1°Plato (~4 gravity
points) prior to full attenuation.
You may have to do a forced fermentation test to determine what your
final gravity should be with the yeast strain you have chosen. To learn how to do a forced fermentation
test, click here.

18.
For
secondary fermentation in a keg, purge the receiving keg by filling the keg
to the rim with sanitizer and then displace the sanitizer with CO2. You will have to cut the gas tube short to
allow you to fill the keg as close to the rim as possible. You may also have to pressurize the keg with
some CO2 to ensure that it seals.

Commerical Spunding Valve

19.
After you
finish racking to the keg, attach a spunding valve to the “beer out” valve
on the keg. For instructions on how to
fabricate a spunding valve, click here.

A spunding valve is basically a
pressure gauge and a pressure relief valve connected by a wye to a liquid quick
disconnect. It provides a way to
naturally carbonate the beer and is a very important tool for controlling
oxygen ingress for homebrewer.

By adding
active yeast to the secondary fermenter, the final oxygen level after
fermentation, conditioning, clearing and carbonation will be very close to
zero.

20.
Use the
secondary fermenter as your serving keg.
If you feel you carried over too much yeast and are worried about the
off flavors of yeast autolysis, transfer to a keg purged in the same manner as
you purged the original spunding vessel (secondary fermentation keg).

The main problem here is that you won’t have
any active yeast available to consume the oxygen that gets into the beer. If you
choose to bottle your beer, use a counter-pressure bottle filler. You still risk transferring the beer without
active yeast but you will have much more control with the smaller volume.

The absolute best way to bottle beer after
brewing with the low oxygen brewing method is to bottle with krausen. Click here to learn all about how this is
done.

The Low Oxygen Brewing (LODO) method of brewing is
relatively new to brewers and homebrewers in America. But, for a chance to completely transform the
flavor of the malts in our beers, I think it is worth trying. A lot of experimentation still needs to be
done.